Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of stock-based compensation expense

Stock-based compensation expense for options granted, RSAs, PSAs and stock purchase rights are reflected in the consolidated statements of operations and comprehensive loss as follows:

	YEAR ENDED DECEMBER 31,
(in thousands)	2018		2017		2016
Selling, general and administrative	$	26,432	$	18,613	$	12,567
Pre-approval commercial manufacturing	2,622		1,359		446
Research and development	9,674		6,106		3,781
Total	$	38,728	$	26,078	$	16,794

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

Weighted average assumptions utilized in the fair value calculation for options to purchase common stock as of December 31, 2018, 2017 and 2016 are as follows:

	YEAR ENDED DECEMBER 31,
	2018		2017		2016
Expected term (years)	6.0		6.0		6.0
Expected stock price volatility	78	%	84	%	84	%
Risk-free interest rate	2.7	%	2.0	%	1.4	%
Dividend yield	—	%	—	%	—	%

Schedule of Stock Options Activity

The following table summarizes the stock option activity under the Plans:

	NUMBER OF SHARES		WEIGHTED AVERAGE EXERCISE PRICE		WEIGHTED AVERAGE REMAINING CONTRACTUAL LIFE (YEARS)	AGGREGATE INTRINSIC VALUE (000’s)
Options outstanding at December 31, 2017	6,457,343		$	22.15
Granted	1,283,884		56.54
Exercised	(616,248	)	8.97
Canceled	(189,860	)	47.85
Options outstanding at December 31, 2018	6,935,119		$	28.96	6.7	$	91,728
Options exercisable at December 31, 2018	4,720,178		$	19.86	5.8	$	86,357

Schedule of Stock Options Outstanding and Exercisable Option Plans

The following table provides additional information about stock options that are outstanding and exercisable at December 31, 2018:

EXERCISE PRICE	OPTIONS OUTSTANDING	WEIGHTED AVERAGE REMAINING CONTRACTUAL LIFE (YEARS)	OPTIONS EXERCISABLE
$0.20 - $10.00	1,579,133	4.2	1,579,133
$10.01 - $20.00	923,137	6.9	701,818
$20.01 - $30.00	1,590,265	5.7	1,522,535
$30.01 - $45.00	968,272	7.9	519,509
$45.01 - $55.00	923,305	8.9	238,307
$55.01 - $73.10	951,007	9.2	158,876
	6,935,119		4,720,178

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity

The following table summarizes the RSA, including PSAs, activity under the Plans:

	NUMBER OF SH ARES		WEIGHTED AVERAGE FAIR VALUE PER SHARE
Nonvested RSAs at December 31, 2017	447,049		$	41.08
Granted	266,514		56.00
Vested	(129,961	)	39.28
Canceled	(10,896	)	52.83
Nonvested RSAs at December 31, 2018	572,706		$	48.18